Welker’s deal with the Broncos is two years at $12 million and could go to $14 million. The Patriots’ initial offer to Welker -- after both sides said all the right things about a future together – was for two years and $10 million.

It is not known what the Patriots’ final offer was. They very well could have matched the offer, but by then Welker could have felt so insulted by a perceived lack of respect that he was walking out the door in any event.

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The move is a surprise, as the likelihood of Welker staying with the Patriots was thought to be strong. But nothing is a given at this time of year in the NFL, especially considering the negotiating history between the Patriots and Welker.

Now, instead of working with quarterback Tom Brady, Welker will be catching passes from Brady’s longtime rival, Peyton Manning. The deal infuses even more potentcy into the offense of the Broncos, who went 13-3 last season, and adds a new dimension to the rivalry between Manning and the Patriots.

“Excited to have Wes join the Broncos. His production and toughness will be a great asset!” tweeted John Elway, the Broncos’ executive vice president of football operations.

Last year, it looked as if there was a long-term deal in place between the Patriots and Welker after the receiver signed his one-year tender via the franchise tag. But it fell apart, and a deal couldn’t be finalized before the league’s deadline in July.

So, Welker played the 2012 season under his one-year franchise deal, earning $9.515 million — more than half of what he’d made in his first five seasons with New England.

At the time he signed his tender last year, Welker tweeted that he was taking a “#leapoffaith,” but his gesture of dedication to his team apparently was not rewarded.

In 2011, New England offered Welker a fully guaranteed two-year, $16 million contract, which he declined.

Losing Welker will be a blow for Brady, who always looked to him on the field and counts him as one of his close friends off it. The durable slot receiver was almost always open when Brady needed a place to throw after a play didn’t go as planned.

Brady signed a contract extension last month that could keep him in Foxborough until he’s 40; there was speculation that the quarterback had asked that Welker be taken care of as part of the deal, but team owner Robert Kraft shot down that notion in an interview with Sports Illustrated.

The Broncos, who tied for the league’s best record at 13-3 before losing to the Ravens in the playoffs, now have Welker in the middle with Demaryius Thomas and Eric Decker on the outside.

At this moment, the Patriots have Brandon Lloyd -- who they would prefer to release -- Matthew Slater (special teamer) and three unknowns, Andre Holmes, Kamar Aiken and Jeremy Ebert, at receiver.

As for where the Patriots go from here, expect them to aggressively pursue Rams receiver Danny Amendola, who is more athletically gifted than Welker but has trouble staying healthy.

The departure of Welker allows the Patriots to go with the offensive approach that they showed against the Cardinals in Week 2 last season: Lloyd or another boundary receiver (perhaps in the draft), Aaron Hernandez in the slot for Welker, Rob Gronkowski at receiver, and players in the ilk of Julian Edelman and Amendola on the other side at receiver.

The Patriots learned last season how valuable Welker is. When other pass catchers, including Hernandez, Edelman, and Gronkowski, were injured, Welker remained Mr. Dependable, and kept his feelings to himself even when it was evident early in the season that he wasn’t intended to be a big part of the offense.

While first Hernandez and then Edelman and Gronkowski went down, Welker remained in the lineup. He wound up finishing tied for second in the league in receptions with 118, and even picked up the slack as the team’s punt returner after Edelman was injured.

Now, the Patriots will have to find ways to replace Welker’s production.

He became the franchise’s career leader in receptions in only six seasons, recording at least 111 catches in all but one of his years with the Patriots (2010), and totaling 672.

Despite being a receiver who fearlessly goes across the middle despite his 5-foot-9-inch, 185-pound frame, Welker missed just three of 96 regular-season games in New England. Edelman, at one point Welker’s presumed successor, has lost 16 games to injury in four seasons.

Welker did sustain a serious knee injury in Week 17 in 2009 and missed the subsequent playoff game. However, he returned for the season opener in 2010.